This invention relates to the housing and transportation of live animals, and more particularly to a novel container for live animals and method of transporting and housing the animals in the container, the container providing ventilation to the animals while serving as a barrier against transmission of microorganisms into or out of the container.
In the transportation of certain live animals there is a need for containers which provide adequate ventilation to allow the animals to breathe, but which provide a barrier against the transmission of germs or other microorganisms. For example, in the transportation of certain laboratory animals, it is important to prevent ingress of germs which may contaminate the animals and impair their usefulness for certain kinds of laboratory research. Prevention of the ingress of microorganisms is also important for protection of the health of a variety of animals. Prevention of the egress of microorganisms is important to protect the health of those handling live animal containers during shipment or otherwise. For certain animals, such as chickens, turkeys, and other poultry, pigeons, doves, canaries, budgerigars, parrots and other psittacine birds, shipment through the mail has heretofore been prohibited because of the risk of infection of those handling the containers.
Shipment of animals may not only expose the animals to disease but also places them under stress. Thus, a need exists not only for containers which protect the animals against contamination but which also serve to minimize the stress experienced by the animals in the course of shipment or housing within a containment system.
Prior to the present invention a variety of containers have been available to animal keepers, breeders and experimenters who wish to hold, restrain, confine or transport animals in biosecure (germ-tight) isolation. Such containers are commonly constituted of non-gas-permeable material and have air vents cut in their sides or top walls. To provide a germ barrier while preserving ventilation, the air vents are covered with a permeable air filter medium sometimes supported on or sandwiched between protective screening material. To prevent microorganisms from bypassing the filter medium, it has been common practice to apply adhesive tape both to the edges of the filter medium and to cover any cracks between the body of the container and the closure.
Trexler U.S. Pat. No. 3,238,922 discloses an axenic container for live animals having a closure in one end which includes a filter which is said to be impervious to microorganisms for admitting air to the interior. The filter is comprised of a porous or fibrous material such as fine glass wool; for example, three layers of Owens-Corning FM-003 fiberglass sandwiched between panels of fine mesh such as conventional metal, plastic or fiber glass window screen.
Schwarz U.S. Pat. No. 3,343,520 describes an animal cage filter cover constructed of a relatively thin sheet of air and gas pervious imperforate material of low structural strength. The sheet or mat of the filter cover is typically comprised of fiberglass and a thermoplastic organic resin such as polyvinyl chloride. The cover is sealed to the body of the cage through a sealing ring of complex cross-sectional configuration.
Lee et al. U.S. Pat. No. 3,528,227 discloses an animal cage having a cover composed entirely of fibrous web material adapted to withstand autoclaving. The fibrous web is constituted of synthetic resin filaments or fibers of polyester or the like, and a thermoplastic such as polyethylene. In a preferred embodiment, a particulate barrier material is sandwiched between two sheets of fibrous material. Despite having relatively large pores (as resulting, for example, from the use of polyester filaments of from 3 to 4 denier), the fibrous material is said to filter out microorganisms effectively by forcing air passing through the filter to follow a tortuous path and thereby reduce its transport velocity.
Lee et al. U.S. Pat. No. 3,613,639 and Lee U.S. Pat. No. 3,528,390 describe containers generally similar to that described in Lee et al. U.S. Pat. No. 3,528,227. In Lee et al. '639 the filter medium comprises a barrier layer of thermosetting resin such as melamine formaldehyde which coats the polyester fibers of the filter material.
Sedlacek U.S. Pat. No. 4,480,587 also describes a polyester fiber filter generally of the same type as that disclosed in the Lee patent. Closure is effected through use of a sealing ring.